Operation method of copper smelting furnace

ABSTRACT

An operation method of a copper-smelting furnace is characterized by including supplying an Fe metal source into a copper-smelting furnace together with a feeding material including copper concentrate and a flux, the copper concentrate including Al, the Fe metal source including an Fe metal of 40 mass % to 100 mass %.

TECHNICAL FIELD

The present invention relates to an operation method of a coppersmelting furnace.

BACKGROUND ART

Recently, a material to be treated in a copper smelting tends to beshifted from a material that is mainly composed of copper concentrate toa material of which a high profit material ratio is increased. However,it was not possible to deal with degradation of an operation(degradation of a slag loss) caused by the shifting. When a high marginmaterial is treated, a generation amount of a hardly meltable substanceof which a main component is magnetite (Fe₃O₄) increases in a furnace.However, a mechanism is not specified. It is possible only to deal withdegradation of a furnace condition after the condition is degraded. In acondition that it is not possible to change a mixing ratio of materials,there are no other effective solving means. The degradation of theoperation is forced for a long time. Therefore, a profit is greatlydegraded.

There is disclosed a method for dealing with a furnace blocking,increase of an intermediate layer and so on that are caused by aperoxide slag (Fe₃O₄ or the like) generated by degradation of a gasphase and a solid phase reaction in a reaction shaft, as a conventionaltechnology (for example, see Patent Document 1). However, in thetechnology, the furnace blocking and the increase of the intermediatelayer are dealt with after the phenomena occur. An effect is small inthe operation condition that the high margin material is increased.Therefore, the technology does not sufficiently deal with the phenomena.

PRIOR ART DOCUMENT Patent Document

PATENT DOCUMENT 1: Japanese Patent Application Publication No. 2005-8965

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

Through a study by the present inventors, it is found out that thehardly meltable substance mainly composed of Al₂O₃ and Fe₃O₄ tends to begenerated when an Al₂O₃ concentration in slag increases because of an Al(aluminum) source in a raw material. And it is found out that a slagloss increases when a separation of matte and slag is degraded. However,there are no effective means for dealing with increase of Al in a rawmaterial.

The present invention was made to solve the above problem, and theobject thereof is to provide an operation method of a copper smeltingfurnace that is capable of suppressing a slag loss.

Means for Solving the Problems

An operation method a copper smelting method according to the presentinvention is characterized by including: supplying an Fe metal sourceinto a copper-smelting furnace together with a feeding materialincluding copper concentrate and a flux, the copper concentrateincluding Al, the Fe metal source including an Fe metal of 40 mass % to100 mass %. The Fe metal source may be supplied when an Al₂O₃concentration in the feeding material exceeds 2.0 mass %. The Fe metalsource may be mixed with the feeding material, and after mixing the Femetal source with the feeding material, the feeding material and the Femetal source may be supplied into the copper-smelting furnace through aconcentrate burner. A grain diameter of the Fe metal in the Fe metalsource may be 1 mm to 10 mm.

Effects of the Invention

According to the present invention, it is possible to suppress a slagloss.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a schematic view of a flash furnace used in anembodiment of a copper-smelting method; and

FIG. 2A to FIG. 2C illustrate a flowchart of a copper smelting using aflash furnace.

MODES FOR CARRYING OUT THE INVENTION

In the following, a description will be given of the best mode forcarrying out the present invention.

Embodiment

FIG. 1 illustrates a schematic view of a flash furnace 100 used in anembodiment of a copper-smelting method. As illustrated in FIG. 1 , theflash furnace 100 has a structure in which a reaction shaft 10, asettler 20 and an uptake 30 are arranged in this order. A concentrateburner 40 is provided on an upper part of the reaction shaft 10.

FIG. 2A and FIG. 2B illustrate a flowchart of a copper smelting usingthe flash furnace 100. As illustrated in FIG. 2A, reaction gas includingoxygen is supplied into the reaction shaft 10 through the concentrateburner 40 together with a raw material for copper-smelting, a flux, arecycle raw material and so on (hereinafter, these solid materials arereferred to as a feeding material). The raw material for copper-smeltingis such as copper concentrate or the like. Thus, the raw material forcopper-smelting causes an oxidation reaction on the basis of thefollowing reaction formula (1) or the like. And, as illustrated in FIG.2B, matte 50 and slag 60 are separated from each other on the bottom ofthe reaction shaft 10. In the following reaction formula (1), Cu₂S.FeSacts as a main component of the matte. FeO.SiO₂ acts as a main componentof the slag. Silicate ore is used as the flux.CuFeS₂+SiO₂+O₂→Cu₂S.FeS+2FeO.SiO₂+SO₂+reaction heat  (1)

For example, it is possible to use oxygen rich air as the reaction gas.The oxygen rich air is air having an oxygen concentration larger thanthat in a natural atmosphere. For example, the oxygen rich gas has anoxygen concentration of 60 volume % to 90 volume %. Therefore, the rawmaterial for copper-smelting can cause sufficient oxidation reaction.

For example, the raw material for copper-smelting includes Cu: 26 mass %to 32 mass %, Fe: 25 mass % to 29 mass %, S: 29 mass % to 35 mass %,SiO₂: 5 mass % to 10 mass %, and Al₂O₃: 1 mass % to 3 mass %. Forexample, copper concentrate having a large amount of Al includes Cu: 24mass % to 30 mass %, Fe: 23 mass % to 28 mass %, S: 29 mass % to 35 mass%, SiO₂: 7 mass % to 12 mass % and Al₂O₃: 3 mass % to 7 mass %.

Al₂O₃ reacts with FeO and forms a complex oxide (FeAl₂O₄) and dissolvesin magnetite (Fe₃O₄). In this case, magnetite spinel is formed becauseof existence of Al₂O₃. And, Fe₃O₄ is stabilized. Thereby, an amount ofsolid Fe₃O₄ increases in a molten metal. And a slag loss tends toincrease. When the molten metal and an Fe metal coexist and an oxygenpotential is reduced, oxidation of FeO is suppressed. And, an allowableconcentration of Al₂O₃ in the slag 60 increases. Thereby, the formationof the complex oxide (FeAl₂O₄) and Fe₃O₄ is suppressed.

On the basis of the knowledge, in order to reduce the slag loss, it isnecessary to increase the allowable concentration of Al₂O₃ in the slag60 when the concentration of Al₂O₃ in the raw material for the coppersmelting increases. On the other hand, it is difficult to suppress theformation of the complex oxide (FeAl₂O4) even if the Fe metal issupplied in the slag 60 after the formation of the matte 50 and the slag60. And it is necessary to adjust the supply position of the Fe metal.And so, in the embodiment, as illustrated in FIG. 2C, an Fe metal sourceincluding the Fe metal is mixed with the feeding material beforesupplied in the reaction shaft 10.

The Fe metal source may be mixed with the feeding material beforesupplied in the reaction shaft 10, by supplying the Fe metal sourcethrough the concentrate burner 40 together with the feeding material. Inthis case, it is possible to finely adjust the supply amount of the Femetal source that is appropriate for Al₂O₃ of the feeding material. Andit is possible to adjust the Fe metal source in real time.Alternatively, the Fe metal source may be supplied through theconcentrate burner 40 after mixed with the feeding material in a mixingprocess. In this case, a mixing condition of the feeding material andthe Fe metal is equalized in a handling in the mixing process. And, abetter effect is achieved.

A material including an Fe metal of 40 mass % to 100 mass % is used asthe Fe metal source. Pig iron or the like may be used as the Fe metal.When the pig iron is used, high reduction effect by the Fe metal isachieved, compared to a case where a recycle material or the like ofwhich an amount of Fe component is small is used. A material includingan Fe metal of 50 mass % to 60 mass % may be used.

When a grain diameter of the Fe metal in the Fe metal source isexcessively small, the Fe metal is oxidized and burns in the reactionshaft 10 because of oxygen in the reaction gas. In this case, thereduction effect may be degraded. On the other hand, when the graindiameter of the Fe metal is excessively large, the Fe metal may settledown to a furnace bottom before achieving the reduction effect. And aphenomenon dedicated to reduction of the furnace bottom may occur. Andso, it is preferable that the grain diameter of the Fe metal in the Femetal source is within a predetermined range. For example, it ispreferable that the grain diameter of the Fe metal in the Fe metalsource is 1 mm to 10 mm.

Fe metal groups having a grain diameter different from each other may bemixed and used as the Fe metal source. For example, when an amount ofAl₂O₃ in the slag 60 in the furnace exceeds 4.5 mass % and the feedingmaterial causing increase of the amount is used, 40 mass % of a first Femetal group having grain size distribution of 5 mm to 10 mm and 60 mass% of a second Fe metal group having grain size distribution of 1 mm to 5mm may be mixed with each other, and a supply amount of the first Femetal group and the second Fe metal group may be 120 kg/h. This isbecause an oxygen potential of a generated molten metal can be kept at alow value, and slag of which an Al₂O₃ amount is large can be reduced bysuspending a relatively large size Fe metal in the slag 60 existing inthe furnace. When an Al₂O₃ amount of the slag 60 in the furnace is lessthan 4 mass % but an Al₂O₃ amount of slag to be generated is going toexceed 4.5 mass %, 20 mass % of a first Fe metal group having grain sizedistribution of 5 mm to 10 mm and 80 mass % of a second Fe metal grouphaving grain size distribution of 1 mm to 5 mm may be mixed with eachother and a supply amount of the first Fe metal group and the second Femetal group may be 60 kg/h. A main reason is that the oxygen potentialin the molten metal just after generated can be kept at a lower value.

Another Fe metal group of which a grain diameter is other than 1 mm to10 mm may be mixed. For example, an amount of a first Fe metal group ofwhich a grain diameter is 1 mm to 10 mm may be 80 mass % in the Fe metalsource, and an amount of a second Fe metal group of which a graindiameter is 10 mm to 15 mm may be 20 mass % in the Fe metal source. Andthe both of the first Fe metal group and the second Fe metal group maybe mixed.

A description will be given of a case where a carbon powder is usedinstead of the Fe metal. When the carbon powder is used, the carbonpowder burns earlier than the copper concentrate in the reaction shaft10. A contribution ratio of the carbon powder as a thermal compensationmaterial increases. Therefore, an effect for suppressing the formationof Fe₃O₄ in the slag is small. Although it is thought that a reductioneffect is achieved with use of a large amount of the carbon powder, anexcessive reaction thermal amount occurs and a thermal load increases.An excessive amount of oxygen is consumed. A treatment amount of thecopper concentrate is reduced. And reduction occurs in production.Moreover, there is a restriction of a gas supply amount in apost-process. Therefore, the treatment amount of the copper concentrateis reduced, and reduction occurs in production. A combustion heat ofcokes that does not contribute to the reduction and burns causesincrease of thermal load of the furnace. This results in a factor of adissolved loss trouble such as a water-cooling jacket for cooling thefurnace or the like.

On the other hand, when the Fe metal is used, the Fe metal drops and isin touch with a droplet of the matte 50 and a droplet the slag 60 thatare just generated in the reaction shaft 10 and have a high temperature.The Fe metal is included in the molten metal. And it is possible tosuppress the formation of Fe₃O₄ caused by Al₂O₃. It is thought that theinfluence of the reduction becomes larger than the influence of Al₂O₃and the formation of Fe₃O₄ is suppressed, when the Fe metal and themolten metal that is just generated and has a high temperature coexistand a reduction degree is increased.

When granular carbon or block carbon is used, reduction of a specificsurface area causes reduction of combustion efficiency of the carbon inthe reaction shaft 10. Therefore, the carbon reaches the molten metal inthe furnace. However, the granular carbon or the block carbon floats ona surface layer of the molten metal because of a specific gravitydifference. Only the surface layer of the slag 60 is reduced. Thecontribution degree of the carbon to the whole of the slag 60 is low.The effect of reducing the influence of Al₂O₃ becomes smaller. On theother hand, when the Fe metal of which a grain diameter is adjusted isused, the oxidation combustion of the Fe metal caused by the reactiongas is suppressed, and settlement of the Fe metal to the furnace bottomis suppressed. Thus, the effect of the suppression of the Fe₃O₄formation by the Fe metal is enhanced.

It is preferable that the supply amount of the Fe metal source isdetermined in accordance with the amount of Al₂O₃ to be formed in theslag 60. It is possible to estimate the amount of Al₂O₃ to be formed inthe slag 60, from the amount of Al₂O₃ in the feeding material. Becausethe recycle material in the feeding material includes Al or Al₂O₃, theamount of Al₂O₃ (amount of Al) is considered. In the followingdescription, the Al₂O₃ concentration (mass %) in the feeding material isa concentration in which Al included in the feeding material (forexample, the recycle material) is converted into Al₂O₃ and is summed.

The concentration of Al₂O₃ in the slag fluctuates in accordance with amixing ratio of the feeding material. However, the concentration ofAl₂O₃ in the slag is approximately 1.7 times to 2.0 times as theconcentration of Al₂O₃ in the feeding material. For example, when theconcentration of Al₂O₃ in the feeding material is 2.2 mass %, theconcentration of Al₂O₃ in the slag is approximately 4.3 mass %. On thebasis of the fact, it is preferable that the supply amount of the Femetal source is 0 kg/h to 20 kg/h, when the supply amount of the feedingmaterial (except for repeated dust) is 130 t/h to 230 t/h (for example,208 t/h), the supply amount of oxygen rich air as the reaction gas ofwhich an oxygen concentration is 70 volume % to 82 volume % is 640Nm³/min to 700 Nm³/min, and it is predicted that Al₂O₃ in the slaggenerated when Al₂O₃ in the feeding material is 2.2 mass % or less is4.2 mass % or less. It is preferable that the supply amount of the Femetal source is 20 kg/h to 42 kg/h, when the supply amount of thefeeding material (except for repeated dust) is 130 t/h to 230 t/h (forexample, 208 t/h), the supply amount of oxygen rich air as the reactiongas of which an oxygen concentration is 70 volume % to 82 volume % is640 Nm³/min to 700 Nm³/min, and it is predicted that Al₂O₃ in the slaggenerated when Al₂O₃ in the feeding material is 2.2 mass % or more and2.4 mass % or less is 4.2 mass % or more and 4.5 mass % or less bycalculation from the Al₂O₃ amount in the feeding material. It ispreferable that the supply amount of the Fe metal source is 42 kg/h to105 kg/h, when the supply amount of the feeding material (except forrepeated dust) is 130 t/h to 230 t/h (for example, 208 t/h), the supplyamount of oxygen rich air as the reaction gas of which an oxygenconcentration is 70 volume % to 82 volume % is 640 Nm³/min to 700Nm³/min, and it is predicted that Al₂O₃ in the slag generated when Al₂O₃in the feeding material is 2.4 mass % or more and 2.5 mass % or less is4.5 mass % or more and 4.7 mass % or less by calculation from the Al₂O₃amount in the feeding material. It is preferable that the supply amountof the Fe metal source is 105 kg/h to 147 kg/h, when the supply amountof the feeding material (except for repeated dust) is 130 t/h to 230 t/h(for example, 208 t/h), the supply amount of oxygen rich air as thereaction gas of which an oxygen concentration is 70 volume % to 82volume % is 640 Nm³/min to 700 Nm³/min, and it is predicted that Al₂O₃in the slag generated when Al₂O₃ in the feeding material is 2.5 mass %or more and 2.6 mass % or less is 4.7 mass % or more and 5.0 mass % orless by calculation from the Al₂O₃ amount in the feeding material. It ispreferable that the supply amount of the Fe metal source is 147 kg/h to160 kg/h, when the supply amount of the feeding material (except forrepeated dust) is 130 t/h to 230 t/h (for example, 208 t/h), the supplyamount of oxygen rich air as the reaction gas of which an oxygenconcentration is 70 volume % to 82 volume % is 640 Nm³/min to 700Nm³/min, and it is predicted that Al₂O₃ in the slag generated when Al₂O₃in the feeding material is 2.6 mass % or more and 2.7 mass % or less is5.0 mass % or more and 5.2 mass % or less by calculation from the Al₂O₃amount in the feeding material.

The concentration of Al₂O₃, Fe₃O₄, Cu or the like in the slag to begenerated may be confirmed by analyzing slag extracted from the flashfurnace 100 or slag extracted from a slag cleaning furnace.

In the embodiment, the Fe metal source of which the Fe metal amount is40 mass % to 100 mass % is supplied into the copper smelting furnacetogether with the feeding material including the flux and the copperconcentrate including Al. Thereby, the oxidation of FeO is suppressed,and the allowable concentration of Al₂O₃ in the slag is enlarged. It istherefore possible to suppress the slag loss. For example, it ispreferable that the Fe metal source is supplied into the copper smeltingfurnace together with the feeding material causing an Al₂O₃concentration in the slag generated by supplying the feeding materialinto the copper smelting furnace is to be more than 4.0 mass %.Alternatively, when the Al₂O₃ concentration in the slag generated bysupplying the feeding material through the concentrate burner 40 exceeds4.0 mass %, the Fe metal source may be supplied into the copper smeltingfurnace together with another feeding material to be supplied afterthat. It is preferable that the Fe metal source is supplied into thecopper smelting furnace together with the feeding material when theAl₂O₃ concentration in the feeding material exceeds 2.0 mass %.

EXAMPLE Example

The copper smelting furnace was operated in accordance with theembodiment. Table 1 shows an operation condition and results. From afirst day to 13th day, an average supply amount of the feeding materialwas 200 t/h, and the Fe metal source was not supplied. From 14th day,the average supply amount of the feeding material was 208 t/h. Theaverage supply amount of the Fe metal source was 42 kg/h. The Fe metalsource was supplied through the concentrate burner after mixing with thefeeding material in advance. The Fe metal source included Fe metal of 55mass % to 65 mass %. The supply amount of the oxygen rich air was 650Nm³/min to 690 Nm³/min.

From the first day to the 13th day, when the Al₂O₃ concentration in thefeeding material increases, the Al₂O₃ concentration in the slag exceeded4.5 mass %. This resulted in the slag loss of 1% or more. This isbecause a high allowable concentration of Al₂O₃ was not achieved withrespect to the slag and Fe₃O₄ was stabilized because of the existence ofAl₂O₃. On the other hand, from the 14th day, the Al₂O₃ concentration inthe slag kept at a high value of 4.3 mass % or more (maximum was 4.7mass %). However, it was possible to keep the slag loss at a low valuethat was approximately 0.8. This is because the generation of Fe₃O₄ wassuppressed, and the allowable concentration of Al₂O₃ in the slag washigh. From the 14th day, it was possible to suppress increasing of theintermediate layer in the flash furnace and the intermediate layer inthe slag cleaning furnace.

TABLE 1

Although the embodiments of the present invention have been described indetail, it is to be understood that the various change, substitutions,and alterations could be made hereto without departing from the spiritand scope of the invention.

The invention claimed is:
 1. An operation method of a copper-smeltingfurnace comprising: mixing an Fe metal source and a feeding materialincluding copper concentrate and a flux, after the mixing, supplying theFe metal source and the feeding material into a copper-smelting furnace,the copper concentrate including Al, and the Fe metal source includingan Fe metal of 40 mass % to 100 mass %, wherein the Fe metal sourcecomprises one or more Fe metal groups, one of the groups having grainsize distribution of a grain diameter of 5 mm to 10 mm, and wherein asupply amount of the Fe metal source per hour into the copper-smeltingfurnace increases as the concentration of Al₂O₃ in a slag increases, andthe supply amount of the Fe metal source supplied into thecopper-smelting furnace is more than 0 kg/h and 20 kg/h or less when thesupply amount of the feeding material, except for repeated dust, is 130t/h to 230 t/h so that a formation of complex oxides FeAl₂O₄ and Fe₃O₄is suppressed by suppressing an oxidation of FeO in the molten metalthrough the mixing of the Fe metal source and the feeding material. 2.An operation method of a copper-smelting furnace comprising: mixing anFe metal source and a feeding material including copper concentrate anda flux, after the mixing, supplying the Fe metal source and the feedingmaterial into a copper-smelting furnace, the copper concentrateincluding Al, and the Fe metal source including an Fe metal of 40 mass %to 100 mass %, wherein the Fe metal source comprises one or more Femetal groups, one of the groups having grain size distribution of agrain diameter of 5 mm to 10 mm, and wherein a supply amount of the Femetal source per hour into the copper-smelting furnace increases as theconcentration of Al₂O₃ in a slag increases, and the supply amount of theFe metal source supplied into the copper-smelting furnace is more than20 kg/h and 42 kg/h or less when the supply amount of the feedingmaterial, except for repeated dust, is 130 t/h to 230 t/h so that aformation of complex oxides FeAl₂O₄ and Fe₃O₄ is suppressed bysuppressing an oxidation of FeO in the molten metal through the mixingof the Fe metal source and the feeding material.
 3. An operation methodof a copper-smelting furnace comprising: mixing an Fe metal source and afeeding material including copper concentrate and a flux, after themixing, supplying the Fe metal source and the feeding material into acopper-smelting furnace, the copper concentrate including Al, and the Femetal source including an Fe metal of 40 mass % to 100 mass %, whereinthe Fe metal source comprises one or more Fe metal groups, one of thegroups having grain size distribution of a grain diameter of 5 mm to 10mm, and wherein a supply amount of the Fe metal source per hour into thecopper-smelting furnace increases as the concentration of Al₂O₃ in aslag increases, and the supply amount of the Fe metal source suppliedinto the copper-smelting furnace is more than 42 kg/h and 105 kg/h orless when the supply amount of the feeding material, except for repeateddust, is 130 t/h to 230 t/h so that a formation of complex oxidesFeAl₂O₄ and Fe₃O₄ is suppressed by suppressing an oxidation of FeO inthe molten metal through the mixing of the Fe metal source and thefeeding material.
 4. The operation method as claimed in one of claim 1,2, or 3, wherein the copper concentrate includes Al₂O₃, and wherein theFe metal source is supplied when an Al₂O₃ concentration in the feedingmaterial exceeds 1.0 mass %.
 5. The operation method as claimed in oneof claim 1, 2, or 3, wherein: the feeding material and the Fe metalsource are supplied into the copper-smelting furnace through aconcentrate burner.
 6. The operation method as claimed in one of claim1, 2, or 3, wherein: the Fe metal source is supplied into acopper-smelting furnace when the Al₂O₃ concentration in the slag exceeds4.0 mass %.
 7. The operation method as claimed in one of claim 1, 2, or3, wherein: the concentration of Al₂O₃ in the slag is estimated from anamount of Al₂O₃ in the feeding material.